It is known that dye images formed from silver halide color photographic materials are sometimes permitted to be exposed to irradiation by light for a long period of time or are left in a dark place for a long time with only a short period of irradiation to light. These conditions can cause severe fading of the dye image. In general, fading under the first circumstance is known as light fading and fading under the second circumstance is called dark fading. When records formed from color photographic light-sensitive material are semipermanently stored, control over such light fading and dark fading to as great an extent as possible and maintenance of three color balance in the fading of yellow, magenta and cyan dye images are necessary so that the initial state of color balance is maintained. However, the degree of light fading and dark fading of yellow, magenta and cyan dye images are different from each other and, thus, the three color balance of yellow, magenta and cyan dye images is destroyed, resulting in degradation of image quality.
Although the degree of light fading and dark fading is naturally different depending on the particular color couplers employed and other factors, in many cases dark fading is apt to occur in the order of cyan dye images, yellow dye images and magenta dye images, and the degree of dark fading in cyan dye images is particularly great compared with that of other dye images. Light fading also tends to occur in the order of cyan dye images, yellow dye images and magenta dye images, particularly when the light source is emitting a large amount of ultraviolet rays.
Therefore, maximum prevention of light fading and dark fading of cyan dye images is necessary in order to maintain three color balance between yellow, magenta and cyan dye images for a long period of time. For the purpose of preventing light fading and dark fading of dye images, various kinds of investigations have been heretofore made, which mainly have followed to approaches to the problem. One approach has been to develop novel couplers which can form dye images having less a tendency to fade. The other approach has been to develop novel additives capable of preventing fading.
A large number of phenol type cyan couplers which form cyan dyes are known. However, 2-(.alpha.-2,4-di-tert-amylphenoxybutanamido)-4,6-dichloro-5-methylphenol as described in U.S. Pat. No. 2,801,171, for example, has the disadvantage that the dye formed therefrom has poor heat fastness while it has good light fastness.
Further, cyan couplers having an alkyl group containing 2 or more carbon atoms substituted on the 3-position or 5-position of phenol are described, for example, in Japanese Patent Publication No. 11572/74, Japanese Patent Application (OPI) Nos. 209735/85 and 205447/85 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), etc. The heat fastness of cyan images formed from these couplers is improved to some extent but still insufficient.
Moreover, 2,5-diacylaminophenol type cyan couplers in which the 2-position and 5-position of the phenol are substituted with an acylamino group are described, for example, in U.S. Patents 2,369,929, 2,772,162 and 2,895,826, Japanese Patent Application (OPI) Nos. 112038/75, 109630/78 and 163537/80, etc. Although the heat fastness of cyan images formed from these 2,5-diacylaminophenol type cyan couplers is improved, their color forming property is poor, cyan images formed therefrom are sensitive to light fading and yellow stain is apt to occur due to irradiation or the unreacted cyan couplers to light. Also, further improvement in heat fastness is required.
1-Hydroxy-2-naphthamide type cyan couplers are generally not satisfactory with regard to both light fading and dark fading.
Further, 1-hydroxy-2-acylaminocarbostyryl type cyan couplers as described in Japanese Patent Application (OPI) No. 104333/81 are excellent in fastness to light and heat, but the spectral absorption characteristics of the color images formed therefrom are not preferred for color reproduction.. In addition, they have the problem that pink stain occurs upon irradiation to light.
Moreover, cyan polymer couplers as described in U.S. Pat. No. 3,767,412, Japanese Patent Application (OPI) Nos. 65844/84 and 39044/86, etc., are excellent in heat fastness under dry conditions, but are poor in heat fastness and color forming property under high humidity.
Furthermore, a method wherein a hydrophobic substance such as an oil-soluble coupler is dissolved in a water-miscible organic solvent and the solution is mixed with a loadable polymer latex whereby the hydrophobic substance is loaded in the polymer latex is described in U.S. Pat. No. 4,203,716, etc. However, the method using such a loadable polymer latex has the disadvantage that cyan images are particularly inferior in light fastness in comparison with a water-immiscible coupler solvent having a high boiling point. In addition, it is necessary to employ the polymer in a large amount in order to load a sufficient amount of coupler to obtain a sufficiently high maximum color density. Still further, Japanese Patent Publication No. 30494/73 describes a photographic material containing a coupler dispersion (diameter of dispersion particles being about 0.5 .mu.m to 5 .mu.m) which is prepared by using an organic solvent-soluble homopolymer of a hydrophobic monomer having a specific structure or copolymer of a hydrophobic monomer having a specific structure and a hydrophobic monomer having a specific structure in place of the coupler solvent having a high boiling point. Improved physical properties of the layer, improved recoloring ability, light fastness and preservability before photographic processing, etc., are achieved. However, in the case wherein the homopolymer of a hydrophobic monomer as described in Japanese Patent Publication No. 30494/73 is employed in place of the coupler solvent, low color forming ability is encountered. This tendency particularly manifests itself (when a color developing solution which does not substantially contain a color forming accelerator such as benzyl alcohol is used), as disclosed in the examples of the above-described patent publication. Another problem is that the stability of the emulsified dispersion is poor.
On the other hand, when using a copolymer containing a hydrophilic monomer such as acrylic acid, etc., the stability of the emulsified dispersion and color forming ability are improved to some extent, but are still insufficient. Further, when the ratio of hydrophilic monomer in the copolymer is increased in order to improve color forming ability, fading, (particularly heat fading at high humidity), is accelerated. In addition, both polymers have the problem of crystallization of couplers during storage of the emulsified dispersion, etc., because the polymers are inferior in preventing the crystallization of couplers.
Further, when the method as described in Japanese Patent Publication No. 30494/73 is applied to cyan couplers, light fastness is severely degraded (1.5 to 3 times) compared with when the couplers are dispersed using a conventional solvent having a high boiling point (known as the oil dispersing method).
In addition, with the method as described in Japanese Patent Publication No. 30494/73, further problem is that the hue of cyan dyes changes over time. More specifically, the spectral absorption of cyan dyes formed upon color development is in a longer wavelength range just after development processing but readily shifts to a shorter wavelength during storage, particularly when exposed to high temperatures.
As described above, couplers that prevent dark fading because of modification of their structure have significant disadvantages with regard to hue, color forming ability, stain, and/or light fastness. Therefore, a novel way to avoid these problems has been desired.
Also, a way to prevent dark fading using other additives or dispersing methods which are known has certain problems and an effective means free from such disadvantages has not been found heretofore.
With regard to color development of silver halide color photographic materials containing oleophilic diffusion resistant type (oil protected type) couplers, various permeating agents for color developing agents have been investigated in order to increase their color forming ability and to shorten processing time. In particular, adding benzyl alcohol to a color developing solution has a large accelerating effect on color formation and, therefore, is widely utilized at present in the processing of color paper, color reversal paper or color positive films for display, etc.
When this approach is used, a further solvent such as diethylene glycol, triethylene glycol, an alkanolamine, etc., is required in order to assist dissolution, since benzyl alcohol has low water solubility. This combination of benzyl alcohol with additional solvents places a high load on the environment due to environmental pollution such as BOD (biochemical oxygen demand) and COD (chemical oxygen demand). Therefore, it is desirable to eliminate these compounds from the processing solution for the purpose of protection of the environment.
Also, it takes a long time to dissolve benzyl alcohol in a developing solution even when such a solvent is employed and, thus, it is preferable not to utilize benzyl alcohol in order to simplify preparation of the solution.
Further, when benzyl alcohol is carried over into the bath following the color developing solution such as a bleaching bath or a bleach-fixing bath, it can cause the formation of leuco dyes of cyan dyes resulting in decreased color density. Moreover, benzyl alcohol retards the rate for running components contained in the developing solution out of photographic materials and sometimes deteriorates the preservability of images in the photographic materials after processing. For these reasons, it is desirable that benzyl alcohol not be used.
Accordingly, a coupler dispersion having improved image preservability as well as excellent color forming property without using benzyl alcohol has been desired.
Therefore, a first object of the present invention is to provide a silver halide color photographic material which can form dye images in which light fading and dark fading are controlled in good balance and which exhibits excellent image preservability particularly when exposed to high temperature and high humidity.
A second object of the present invention is to provide a silver halide color photographic material which can form dye images having good color balance in the fading of yellow, magenta and cyan color images by controlling the degree of fading, whereby excellent preservability is obtained when the photographic material is stored for a long period of time.
Third object of the present invention is to provide a silver halide color photographic material which can form dye images having improved image preservability without adversely affecting the desired properties of the photographic material.
A fourth object of the present invention is to provide a silver halide color photographic material having excellent image preservability which contains a coupler emulsified dispersion which exhibits sufficiently high color forming property even when processed with a color developing solution which does not substantially contain benzyl alcohol and has good stability.
A fifth object of the present invention is to provide a silver halide color photographic material having improved dark fastness without degradation of light fastness of cyan dye images.